Thoughts on high mileage Mustang Cobras

I'm in the market for a 1998 or 1999 Cobra. I love the body on the 1998, but also like the IRS on the 1999. Anyway, I've found a convertible 1998 that is VERY affordable, but it has 100,000+ miles. Is this something that I should avoid completely, or would I be able to maintain it at a reasonable cost? What about the performance? How long can I expect the engine to last? At the price, it would leave some money in reserve.

The drivetrain can be rebuilt but I'd be worried about body rigidity. Those aren't the tightest cars in the world, even in coupe form, even with low miles. I've had two loose convertibles and all that flexing takes a lot away from the experience.

Of course nothing could be like the '89 Camaro convert I drove once. Those cars came from the factory clapped out and this one had 60k hard miles. Boy what a ride that was. Must be like what you'd get if you strapped a small block to a shopping cart.

I'm not so sure a Cobra convertible has necessarily been driven hard, at least not by its original owner. Most Mustang 'vert owners I see are guys having a midlife crisis.

The more I think about it the more I like it, assuming you get it for the right price and that you're okay with the idea that after you're done with it it'll be virtually worthless.

Those cars weren't cheap when they were new and if that didn't keep young hotshoes out of the driver's seat the insurance premium would. So assuming you're buying from the original owner I think you're dealing with someone with some maturity--some, anyway. Enough to maintain it and not beat it senseless.

I drove a Mustang LX 5.0 convertible once, a '90 or so, and it was a righteous experience. The '93-up lost some of the fun factor but gained some rigidity and refinement. That's important in a convertible.

Check availability of service records, how often the oil/filter were changed and type of oil,(conventional or synthetic)I have a 97 GT purchased new and now has 93,000 miles and kept the oil/filter changed (synthetic oil and sometimes regular conventional oil) and have not experienced any engine problems (ie; leaks or excessive oil consumption) And I do drive the car resonably hard.

Depends on what you consider high miles for me 250,000 miles is high and 93,000 is just getting broken in but there are serious differences in the design criteria in Cobras 4.6 liter 32v and something like a 4.5 liter Q or Lexus which can easily perform near new at 250k on a diet of Syn fluids.

Mpost wear occur when new from day one on cold low pressure starts.

The main criteria is the crank shaft and rod bearing clearances when new and the type and hardness of rings.

my old Acura Integra. I read the article you recommended, but I confess I didn't understand it all. What is the best way of protecting the car from cold starts? Are additives like Lucas Oil stabilizer the way to go? Or a synthetic/regular oil blend? My plan was to use regular oil and a regular oil filter but to change the oil every 2000 miles. Also, to use Everwear additives or Lucas additives.

"serious differences in the design criteria in Cobras 4.6 liter 32v and something like a 4.5 liter Q or Lexus which can easily perform near new at 250k on a diet of Syn fluids."

Meaning what? That the Lexus and Infiniti motors are better? I always thought the Ford DOHC 4.6L was a pretty stout motor. Compared to the Ford SOHC 4.6L commonly found in service vehicles approaching and surpassing 300,000 miles, the DOHC 4.6L is pretty overbuilt. It's also handbuilt. I don't see any problem with this motor going the distance if it was maintained and not abused.

300K is pretty unrealistic in any car. One always "hears about" 300K engines but one rarely sees them....now and then. Shooting for the outside statistic of probability is not realistic is all I'm saying. Yes, some men live to be 101. Don't count on it, though.

Engine durability is very much tied to machining tolerances, parts quality and engineering. I think Q45man was saying that a Q45 or Lexus motor is probably built to better tolerance and metallurgy than a Mustang and I would agree with that as being likely.

In the "old days", car engines were pretty "sloppy" in tolerance and this is why a 60s muscle car engine or even expensive foreign car has had it at 100K. The bores were about as straight as a bent soda straw. They had to be built "loose".

So the brute "strength" of the engine is not the issue, or its weight, or whether a little old man put it together-- but tolerances and machining processes do make a big difference for the "long haul". This is why modern engines have such long service intervals, they are built much tighter. And some are built tighter and better than others, as you might expect. If your car company wants to save $5 a car on bearings, or $3 a car on machining costs, the average driver is not going to suffer as he often trades the car in at 3-5 years. But in the long haul, any sloppiness or cost cutting is going to tell.

"I think Q45man was saying that a Q45 or Lexus motor is probably built to better tolerance and metallurgy than a Mustang and I would agree with that as being likely."

Key word: "probably". If the Lexus and Infiniti engines are built to better tolerances, then there should be proof of this somewhere. While I don't doubt that the Lexus and Infiniti engines may be built tighter, my point was that the Ford DOHC 4.6L cobra engine is not your average run-of-the mill Ford engine. It is a hand built specialty motor. When you say that the Lexus and Infiniti engines are tighter, I expect proof to back up that claim. For now, it's just speculation based on the image of Ford, Lexus, and Infiniti.

before I got out of the car business, I can assure you that even though the 4.6 is much better than the old 302/351 design, it bears no quality similarities with Lexus, Toyota, Nissan and Honda engines.

"With over 7,500 cars bought and sold before I got out of the car business, I can assure you that even though the 4.6 is much better than the old 302/351 design, it bears no quality similarities with Lexus, Toyota, Nissan and Honda engines."

How many of those cars were DOHC Cobras with high mileage? We're not talking about the regular 4.6L. While I don't doubt that Lexus and Infiniti motors are tight, I would expect somebody to be able to back up the claim that they are built tighter than the Ford DOHC 4.6L. I don't see how you can "assure" anyone of anything without being able to prove it.

people are funny here. You have people who obviously don't have experience of any significant level in the car business arguing with people with significant experience. You only response is "show me statistics".

How many Cobras are over 100,000 miles? I haven't seen one yet. I hope no one miles up a collectable car like that - that is just wrong.

I just wanted proof. I don't see how anyone can make a claim like that if they DON'T KNOW. You need to look up the words "speculation" and "fact" in the dictionary. I have worked in the car business. I worked at a service station doing minor work for 6 years while in High School and College. I took automotive mechanics classes in High School. That being said, the experience doesn't qualify me to make statements about engine tolerances on engines that I have never worked on and neither does the experience of buying and selling cars. If someone told me that an Acura 1.8L VTEC motor is tighter than a GM 2.5L "iron duke", I'd take their word for it. This comparison is different. I would not be surprised at all to find out that the Lexus/Infiniti motors are tighter but I just don't know for sure and NEITHER DO YOU.

I wasn't trying to point out that my experience is relevent, just pointing out that I have worked in the automotive business. I KNEW you would say something about that, that's why I said it. My point was that your experience of buying and selling 7500 cars is just as irrelevant as mine. You can rattle off credentials all you want, hell, I could say that I am the Prime Minister of Siberia, this is the internet.

"I believe I can tell you that Texus/Infiniti motors are built to tighter specs than a 4.6."

So I should believe it because you say so? Sorry, it doesn't work that way and please get one thing straight: This is not just a "4.6" we are talking about, it's the 4.6L DOHC. Yes, they are completely different. They don't even share the same block. At best, your comments are YOUR educated guesses, but they are still guesses. Being an automotive engineer, you should know that the words "guess" and "tolerances" should not be used in the same sentence.

BTW, what the heck is someone with a Master's Degree in automotive engineering selling cars anyway?

I don't sell cars. I haven't sold cars since 1994. I consult for a lawfirm on dealer fraud, lemon law and breach of warranty cases. I tesitify as an automotive expert in automotive repair and maintenance, vehicle appraisal and delaership sales and service policy.

I really don't care if you don't believe me. The hosts here on Edmunds have my curriculum vitae - it's also a matter of court record in PA, NJ and DE.

I am a hardcore Mustang owner - I'm on my 5th one now and will get an '03 Cobra next Spring, after the flurry is over and I can get one at a normal price. I understand the 4.6 Cobra motor. I also know the block casting techniques are no different than that of Ford's other engines.

You were talking about longevity of various makes of vehicles. How do you figure a person with thousands of vehicle appraisals under his belt wouldn't know what lasts and what doesn't? I say he'd better know when he's spending a dealer's money, or he won't have a job for long.

Well, look, we can't bust apart engines on line, so forget the argument. You'll just talk to each other until you are blue in the face.

The best "proof" I can offer you isn't proof at all, but history. I've busted apart engines of various types and if I went by the past, a Japanese engine is machined and made to a higher standard than an American engine. There is certainly that "pattern" in my own experience. If you build lots of engines, I would certainly listen to a counterargument--then we'd be on the "same page" regarding experience, or you'd even be ahead of me and I'll respect that. But so far, the professionals I know would, I feel, back me up. Also, I've been appraising cars for almost 20 years, and this experience backs up my assumptions.

Could a certain Ford engine go against this pattern? Sure.Of course. I'm just betting on the odds that it doesn't, but sure. I'm not saying the people at Ford don't know HOW to build a longer-lived (notice I didn't say "better") engine than Lexus, I'm just saying they choose not to, for cost reasons for one thing.

So let's call it "an educated guess" and no more than that. Which is what I meant by a Lexus engine being more "likely" to get to 300K than a Mustang's.

I'd also like to add that some of the world's greatest and most competitive engines would never get to 300K. Long mileage is not a sign of a 'great engine" in my book. I doubt a brand new Ferari engine would ever get near that mileage, and I know that famous engines like the Mercedes Gullwing, Jaguar XKE, etc etc., could barely do 1/3 that.

Last of all, being "hand-built" is not a plus for longevity or a minus. A man only assembles what the machines have made.

"How do you figure a person with thousands of vehicle appraisals under his belt wouldn't know what lasts and what doesn't?"

You said it yourself. You've never seen a Cobra with that many miles. Cobras with a lot of miles are rare, so how would you know how long the motors last? Have you rebuilt a Lexus, Infiniti, or Ford DOHC V8? How can you compare tolerances between them?

"I also know the block casting techniques are no different than that of Ford's other engines."

The block is aluminum and cast by Teksid of Italy, the same folks that do the Ferrari Formula 1 blocks. The SOHC block isn't. The crank comes from Gertach in Germany. If they are the same, why the need for the experience of these folks?

buying a high mileage Cobra. I thought it was an interesting topic since there aren't too many Cobra DOHC 4.6L engines with many miles on them yet. So far, the speculation of whether or not it is going to last that long is based on other Ford engines. It was relevant to point out that the Cobra 4.6L DOHC engine is not like other Ford engines. Of course reliability depends on how the engine was treated during those miles, but engine design is a major factor. So far, no one has been able to prove or disprove the idea that the Japanese V8s are better with regards to manufacturing tolerances or long term reliabilty. Generally, I know that Japanese designed engines are better than Domestic designed engines, but I think this comparison is unique.

I know I put 209k miles on my 88 Acura Integra. The engine was still running pretty well at 209k, but the a/c went, so rather than replace it I traded the car in on a Honda Civic HX. I traded the Civic in at 90k miles, and the engine was running about perfect. So I have some limited experience putting miles on cars.

Back in the eighties, I remember American cars had a horrible reputation for reliability. That kept me away from them until this September, when I got a 03 GT. I am very interested to see how this car holds up when it gets mileage on it.

But I notice you guys are drawing a distinction between the SOHC and the DOHC. Wouldn't the SOHC last longer, since it is a simpler design (all other things being equal)?

Let's put aside 300k miles for a minute, is 200k miles unreasonable assuming proper maintenance for either of the 4.6 Ford engines? (Also, can we say some nice things about Ford engines because they are, well, Ford engines and not rice burner engines.)

of 150,000 and 200,000 mile SOHC 4.6s in service. Since the Caprice died in 1996, law enforcement has purchased Crown Vics for 95% of their fleets - a few Impalas, Intrepids and Camaros thrown in. Most retired PD cars become taxis - I saw a 325,000 Crown Vic here in Philly - looked like a reman motor, but two engines in 325K is still great.

My only concern about the DOHC 4.6 is that it's high strung. Then again, Saleen supercharges them (not easy on the bottom end) - so does Steeda and Roush. Another choice (other than the '03) is to buy a used up '99-00 (if I can find one) and drop in a crate motor from Probe Industries with a Vortech or Paxton. Could be fun.

Well, very high performance engines are generally built loose, yes, for safety and reliability, but your average passenger car engine these days is built to a pretty tight tolerance. In the 60s, I think they were just sloppy, that's all, with no intention one way or the other. That's all the skill they had, most of them.

As far as longevity goes, any car that is super or turbo charged is going to loose some engine life. That's just the laws of physics. It might only be 10-15%, and you the driver may never have to "pay the price" if you trade it in after a couple years, but if you stress and engine for more power you are going to lose something in the bargain.

As for a Ford dohc going 200K miles, the answer is "it depends". Will all of them get that far---no, I don't think so, because most cars don't get that far---they are crashed, stolen, rusted or some other major component or combination of components fail and cause the car to be retired prior to engine failure.

If you scan the average junkyard, you will not see very many 200K+ cars, because there are many factors that send a car to the grave.

But certainly will good care and good luck, 200K is no big deal on any modern V8---but it's the exception, not the rule.

All I want to stress is this: If you're buying a car with 150K on it, you are buying a car that is pretty much used up. If it has 100K, it's at least 1/2 used up, maybe 2/3. A car is a "total package", not just an engine. After 150K, you're going ot have to start re-making it, piece by piece, as you drive.

All specs from the 1992 Q45 shop manual!!!!!!!Each crankshaft bearing has 6 choices [grades from 0-6] increments of 0.0001". The crankshaft maximum taper is 0.0002".The main bearing clearance is specified to be 0.0005" to 0.0012" with a recommended 0.0008" and an upper limit of 0.002".The connecting rod bearing clearance is specified at 0.0013" and a max limit of 0.0026".There are 5 grades of pistons available in 0.0004" increments and the wrist pin fit is specifyied at zero to a max of 0.0002".

I can assure you that an 8-13 MICRON fit is at least twice as tight as a Cobra engine is built too. The Yamaha SHO V8 closest was 20 microns!Each Q engine has a series of 16 codes stamped into the block showing the grade of bearings and pistons utilized in the build......remember this was Nissan first V8 and they tried to do it right from the forged crank to forged rods to special cast pistons to the expensive bearing girdle [main bearing beam] to attach the 6 bolts per cap.name any engine designed in 1988 that had 6 bolts per main].By the way the exhaust values are sodium filled stainless steel, the intakes are just stainless. Viton seals are used thoughout [each cost $8.00 for each of 32 valves].

We have at least 7 clients with Q engines over 240,000 miles so 300,000 is easily obtain same with 4 90 LS400 over 250,000 miles.

The ones maintained don't smoke, the bad ones do and I have seen 96Q destroyed at 136,000 miles by lack of oil changes.